NASA paid Morton Thiokol Inc. nearly $423 million in 1988, most of which went to pay for redesigned space shuttle booster rockets, company officials say.

The aerospace company ranked third, behind the Jet Propulsion Laboratory in Pasadena, Calif., and Lockheed, Sunnyvale, Calif., in terms of dollars received from NASA during the fiscal year that ended Sept. 30, said Morton Thiokol spokesman Rocky Raab.In all, Raab said, Morton Thiokol got about 6 percent of the space agency's big contract payments.

The amount was a large jump from the $286 million received in 1987, which was a drop from almost $320 million in 1986 and more than $334 million in 1985.

Raab said the fluctuations resulted from the Jan. 28, 1986, shuttle Challenger explosion. A presidential commission found that a faulty booster rocket seal caused the disaster.

In 1987, with manned space flights grounded while new, safer boosters were designed, production was down at Morton Thiokol's rocket plant 25 miles west of Brigham City.

Raab said more money came from NASA in 1988 than the year earlier as the redesign effort culminated in the testing of the new 126-foot-long rockets and resumption of flight-set deliveries as shuttle missions resumed.